Research On Ground Fault Location In Distribution Network

Single-phase grounded fault happens most frequently in the non-solidly earthed network with the Probability up to 80 percent. However,when a single phase-to-earth fault occurs,they are rather difficult to identify the fault feeder because the fault currents are much too small,especially under disturbance and detecting error. How to detect the fault correctly and location the fault position has been an important research task of small current grounding system.Based on the current research situation and development trend in single phase-to-earth fault of single-phase grounded system,as well as the analysis of the transient and stable features of fault information on fault line in small current earth system,this paper puts forward a method for fault location in small current power system called "Comprehensive Analysis Law"."Comprehensive Analysis Law" includes four criterions of locating fault point–"Transient zero sequence current Amplitude law","Stable Base wave zero sequence current Phase law","Seventh harmonic zero sequence current Phase law"and"S injection law", and uses selectively in accordance with certain application principles, as a result the law will not only make up the blemishes existing in current methods for single-phase fault location in small current grounding system,but also locate the fault point to minimal fault isolating unit on fault line.In this paper, MATLAB toolbox is used to build a simulation model of 10kV substation, so as to simulate the fault processes of neutral ungrounded system and neutral point earthed via arc-suppression coil system under different fault conditions, and study the hardware architecture of single-phase to earth fault location system of the distribution network based on "Comprehensive Analysis Law".